This invention relates to a splicing unit for connecting together the ends of two lengths of plastics zipper such as is used for reclosable plastics bags and the like. The invention is also concerned with a method of splicing together, i.e. connecting, two ends of such zipper material.
In the manufacture of plastics bags using reclosable fasteners the zipper which is used and which carries male and female profiles is wound on reels, from which it is unwound for guidance towards the bag-making apparatus. Currently, when a reel of zipper is exhausted, it is necessary to switch over to another reel. This can be a time-consuming operation, requiring the new zipper to be correctly fed into and established within the bag-making apparatus.
It is an object of the present invention to speed up the changeover operation from one length of zipper to another when changing reels.
In accordance with the present invention there is provided a method of connecting two lengths of zipper material, each length comprising two interengageable parts, and each part comprising a base carrying respective male and female profiles, the method comprising the steps of bringing the trailing end of one length and the leading end of the other length into abutting relationship with the male and female profiles engaged, bridging end zones of the respective lengths with sealing material, and sealing the bridging material to the lengths of zipper material to effect a connection therebetween.
Preferably, each base has flanges on each side of the male/female profiles, and the sealing material is laid over the end zones with the respective flanges maintained separated.
Preferably, the heat-sealing material is overlaid on the outside surface of both bases and a heat sealing operation is carried out on both surfaces simultaneously.
Also in accordance with the present invention there is provided an apparatus for connecting two lengths of zipper material, each length comprising two interengageable parts, and each part comprising a base carrying respective male and female profiles, the apparatus comprising means to hold the lengths of zipper material in abutting end-to-end relationship with the male and female profiles engaged, means to apply sealing material to the end zones of the lengths to bridge the lengths, and sealing means arranged to effect sealing of the sealing material to the bases to connect the lengths together.
Preferably, each base has flanges on each side of the male/female profiles, and separating means are provided for entry between the opposing flanges to maintain the flanges apart during the sealing process.
Preferably, the separating means comprises dividing plates which divide the flanges of the zipper prior to the sealing treatment, in order to prevent the flanges from being sealed one to another when the sealing operation is carried out, for example by heating.
The connection of the two lengths of zipper in accordance with the invention is essentially a butt splicing operation.
In order that the invention may be more fully understood, one presently preferred embodiment in accordance with the invention will now be described by way of example and with reference to the accompanying drawing.